John and Kevin each bought apples at the store. John bought three more than twice the number of apples Kevin bought. If they bought 21 apples combined, how many apples did Kevin buy?

Let x be the amount of apples that Kevin bought.

It says that john buys three more than twice the amount of apples that kevin buys, so 3 + 2x apples.

They bought 21 apples total, so x + 3 + 2x=21

Collecting like terms gives 3x+3=21

Subtracting 3 from both sides gives 3x=18 and then dividing both sides by 3 gives x=6

x is the amount of apples kevin bought, so kevin bought 6 apples